AmpC Production Research Articles

Antibiotic Susceptibility Profiles and Resistance Mechanisms to β-Lactams and Polymyxins of Escherichia coli from Broilers Raised under Intensive and Extensive Production Systems.

The intensive and extensive broiler production systems imply different veterinary interventions, including the use of antimicrobials. This study aimed to compare the antimicrobial susceptibility profiles of Escherichia coli isolated from both systems, characterize resistance mechanisms to β-lactams and polymyxins, and identify genetic elements such as integrons. E. coli isolates recovered from broiler cecal samples were assayed for antimicrobial susceptibility through the broth microdilution technique. The molecular characterization of acquired resistance mechanisms to β-lactams and colistin and the detection of integrons was performed by a multiplex PCR. For most antibiotics tested, the prevalence of reduced susceptibility is higher in commensal and extended-spectrum β-lactamases (ESBL)/AmpC producers from broilers raised in the intensive system, compared with those raised under extensive conditions. SHV-12 was the most common ESBL enzyme found in both production systems. Other ESBL variants such as CTX-M-1, CTX-M-55, CTX-M-14, CTX-M-32, CTX-M-9, TEM-52, and plasmid-encoded AmpC enzyme CMY-2 were also present. MCR-1 was identified in a colistin-resistant isolate from broilers raised under the intensive system. This study highlights the differences in E. coli antibiotic susceptibility from both production types and emphasizes that a great deal of work remains to decrease consumption and antimicrobial resistance levels.

Rapid Detection of Plasmid AmpC Beta-Lactamases by a Flow Cytometry Assay.

Plasmidic AmpC (pAmpC) enzymes are responsible for the hydrolysis of extended-spectrum cephalosporins but they are not routinely investigated in many clinical laboratories. Phenotypic assays, currently the reference methods, are cumbersome and culture dependent. These methods compare the activity of cephalosporins with and without class C inhibitors and the results are provided in 24–48 h. Detection by molecular methods is quicker, but several genes should be investigated. A new assay for the rapid phenotypic detection of pAmpC enzymes of the Enterobacterales group-I (not usually AmpC producers) based on flow cytometry technology was developed and validated. The technology was evaluated in two sites: FASTinov, a spin-off of Porto University (Portugal) where the technology was developed, and the Microbiology Department of Ramón y Cajal University Hospital in Madrid (Spain). A total of 100 strains were phenotypically screened by disk diffusion for the pAmpC with the new 2 h assay. Molecular detection of the pAmpC genes was also performed on discrepant results. Forty-two percent of the strains were phenotypically classified as pAmpC producers using disk diffusion. The percentage of agreement of the flow cytometric assay was 93.0%, with 95.5% sensitivity and 91.1% specificity. Our proposed rapid assay based on flow cytometry technology can, in two hours, accurately detect pAmpC enzymes.

Genomic Characterization of International High-Risk Clone ST410 Escherichia coli Co-Harboring ESBL-Encoding Genes and blaNDM-5 on IncFIA/IncFIB/IncFII/IncQ1 Multireplicon Plasmid and Carrying a Chromosome-Borne blaCMY-2 from Egypt.

The accelerated dispersion of multidrug-resistant (MDR) Escherichia coli due to the production of extended-spectrum β-lactamases (ESBLs) or AmpC enzymes has been noted in Egypt, presenting a serious treatment challenge. In this study, we investigate the prevalence of ESBLs and AmpC enzymes among 48 E. coli isolates collected from patients with urinary tract infections admitted to a teaching hospital in Alexandria. Phenotypic and genotypic methods of detection are conducted. Isolates producing both enzymes are tested for the mobilization of their genes by a broth mating experiment. Whole genome sequencing (WGS) is performed for isolate EC13655. The results indicate that 80% of the isolates are MDR, among which 52% and 13% were ESBL and AmpC producers, respectively. Conjugation experiments fail to show the mobilization of blaCMY-2 in EC13655, which was chosen for WGS. In silico analysis reveals that the isolate belongs to a ST410-H24Rx high-risk clone. It coharbors the ESBL-encoding genes blaCTX-M-15, blaTEM-1, blaOXA-1 and blaNDM-5 on an IncFIA/IncFIB/IncFII/IncQ1 multireplicon plasmid. The chromosomal location of blaCMY-2 is detected with a flanking upstream copy of ISEcp1. This chromosomal integration of blaCMY-2 establishes the stable maintenance of the gene and thus, necessitates an imperative local surveillance to reduce further spread of such strains in different clinical settings.

Phenotypic Characterization of Virulence Factors and Antibiogram of Klebsiella pneumoniae Isolates from Various Clinical Samples – A Cross Sectional Study

K. pneumoniae is known to cause hospital and community acquired infections. It is usually associated with upper & lower respiratory infections, septicaemia, urinary tract infection, wound infections, neonatal sepsis, meningitis, and endophthalmitis. The virulence factors play a role in its existence in different environmental conditions and therefore help in establishing Klebsiella pneumoniae infection in the human body. Multi drug resistant Klebsiella pneumoniae is an increasing threat to human health. Klebsiella pneumoniae is one of the species recognized as nosocomial pathogens that exhibit multidrug resistance and virulence in ESKAPE group as per WHO. The study was conducted to determine the various virulence factors & the antimicrobial pattern of Klebsiella pneumoniae isolates. A cross sectional observational study, conducted in Department of Microbiology of R.L. Jalappa Hospital and Research Centre, Kolar, Sample size of 150. All 150 Klebsiella pneumoniae isolates collected for the study, The Klebsiella pneumoniae isolates which were positive for various virulence factors were as follows on hemolysis 7(4.66%), capsule 150(100%), Hypermucoviscosity formation 66(44%), biofilm production 81(54%), siderophore production 110(73.33%), protease 135(90%), gelatinase 126(84%), lipase production 119(79.33%), lecithinase activity 82(54.66%). The drug resistance klebsiella pneumoniae were as follows: ESBL producers 24(16.67%), AmpC producers were 22(14.67%), MDR 116(74.20%), extensive drug resistant (XDR) 30(20%), pan drug resistant (PDR) 42(28%), Carbapenem resistance 65.33% reported. The increasing coexistence of virulence factors & antimicrobial resistance pattern is of particular concern. Hence active surveillance for antimicrobial resistance & virulence determinants is imperative now to implement effective control measures to prevent the rapid spread of drug resistance.

Activity of mecillinam against carbapenem-resistant Enterobacterales.

BackgroundDespite the fact that carbapenem-resistant Enterobacterales (CRE) mostly cause urinary tract infections (UTIs), only few studies have focused on the efficacity of mecillinam against these CRE.ObjectivesTo evaluate the mecillinam susceptibility of a huge collection of CRE, including carbapenemase-producing Enterobacterales (CPE) and non-CPE (ESBL and AmpC producers with decreased permeability of the outer membrane).MethodsA total of 8310 non-duplicate clinical CRE, including 4042 OXA-48-like producers, 1094 NDM producers, 411 VIM producers, 174 KPC producers, 42 IMI producers, 153 multiple-carbapenemase producers and 45 isolates producing other types of carbapenemases (such as IMP-like enzymes or GES-5), were included in the study. WGS was performed on all CPE using Illumina technology. Categorization of susceptibility to mecillinam was performed using disc diffusion (mecillinam discs at 10 μg; I2A, France) according to EUCAST recommendations. The results were interpreted according to EUCAST guidelines (S ≥15 mm).ResultsSignificantly higher susceptibility rates were observed for carbapenem-resistant Proteus spp. (85%) and carbapenem-resistant Escherichia coli (84%), which are the two most common species responsible for UTIs, than for Klebsiella pneumoniae (67%), Enterobacter cloacae complex (75%), Citrobacter spp. (65%), Serratia spp. (34%) and Morganella morganii (12%). Susceptibility rates were 84%, 71% and 91% for OXA-48-like, NDM and IMI producers and 70% for non-CPE CRE. Mecillinam was less active against VIM and KPC producers (14% and 0%, respectively).ConclusionsMecillinam might be an alternative for the treatment of infections due to CRE, particularly UTIs, except for VIM and KPC producers and for M. morganii and Serratia spp species.

AmpC Beta-Lactamase Prevalence in Isolates of Escherichia coli and Klebsiella pneumoniae in Enugu, Nigeria

Background: Pathogenic bacteria with beta lactamase-resistant determinants have emerged, posing a worldwide health threat. They confer resistance to a large array of \(\beta\) -lactam agents and \(\beta\)-lactam inhibitors. Aim: This study evaluated the prevalence and resistance profiles of plasmid-mediated AmpC \(\beta\) -lactamase producing isolates among Escherichia coli and Klebsiella pneumoniae from clinical and environmental sources in the Enugu metropolis. Methodology: The work was done in the Microbiological Laboratory of the University of Nigeria Teaching Hospital Ituku-Ozalla. A total of 150 non-duplicate isolates processed in the microbiology laboratories of three referral hospitals and some private laboratories were used in this study including 85 and 65 isolates of Escherichia coli and Klebsiella pneumoniae respectively. Isolates were identified and characterized using standard microbiological protocols. Antimicrobial susceptibility was performed using the Kirby-Bauer disc diffusion procedure. Phenotypic detection of AmpC \(\beta\)-Lactamase production was determined using Cefoxitin/Cloxacillin double-disc synergy (CCDST). Results: Of the 67 isolates of E. coli from clinical samples, AmpC production was confirmed in 20(29.9%) and of the 18 isolates from environmental sources, only 5(27.8%) were confirmed. Of the 60 isolates of Klebsiella pneumoniae from clinical samples 16(26.6%) were AmpC producers while 1(20%) out of the 5 isolates from environmental samples was an AmpC producer. The prevalence of AmpC \(\beta\)-lactamase producers was 28%. There was no statistical difference in the proportion of AmpC producers in clinical and environmental isolates in E.coli and Klesiella pneumoniae p = .86 and p = .74 respectively. Antimicrobial resistance was high in both AmpC and non-AmpC \(\beta\)-lactamase producers. Impenem’s susceptibility was found in 75.4 percent of the isolates.
 Conclusion: This research revealed a high prevalence of AmpC beta-lactamase in the Enugu metropolis. The identification of AmpC beta-lactamase enzymes regularly is crucial to preventing therapeutic failures. The proper usage of antimicrobial drugs is critical.

Extended-Spectrum β-lactamases and AmpC Production among Uropathogenic Isolates of Escherichia coli and Antibiogram Pattern

Emergence of drug resistance in Escherichia coli due to various mechanisms makes the treatment choices very limited. The objective of this research was to investigate extended-spectrum beta-lactamases (ESBLs) and AmpC lactamases in E. coli isolates from urinary tract infections (UTIs) and to assess their antibacterial susceptibility patterns in a health-care context. Atotal of 70 E. coli isolates from clinically assumed cases of UTI patients during the 9months period. The isolates with bacteriuria (105 CFU/ml) were identified. ESBL and AmpC were detected phenotypically. Out of the 70 isolates of uropathogenic E. coli, ESBL production was detected in 34(48.6%) isolates and AmpC producer in 27(38.6%) of isolates in which 14(20%) of them showed coexistence phenotype of both ESBLs and AmpC and 23(32.9%) E. coli isolates were both ESBL and AmpC non-producer. The findings donated information regarding drug resistance. The level of resistance recorded in ESBL-and AmpC-producing uropathogenic E. coli of this study was raising; therefore, it is crucial to have a strict infection control measures and routine monitoring of ESBL-and AmpC-producing bacteria in clinical laboratory.

Efficacy and In Vitro Activity of Novel Antibiotics for Infections With Carbapenem-Resistant Gram-Negative Pathogens.

Infections by Gram-negative multi-drug resistant (MDR) bacterial species are difficult to treat using available antibiotics. Overuse of carbapenems has contributed to widespread resistance to these antibiotics; as a result, carbapenem-resistant Enterobacterales (CRE), A. baumannii (CRAB), and P. aeruginosa (CRPA) have become common causes of healthcare-associated infections. Carbapenems, tigecycline, and colistin are the last resource antibiotics currently used; however, multiple reports of resistance to these antimicrobial agents have been documented worldwide. Recently, new antibiotics have been evaluated against Gram-negatives, including plazomicin (a new aminoglycoside) to treat CRE infection, eravacycline (a novel tetracycline) with in vitro activity against CRAB, and cefiderocol (a synthetic conjugate) for the treatment of nosocomial pneumonia by carbapenem-non-susceptible Gram-negative isolates. Furthermore, combinations of known β-lactams with recently developed β-lactam inhibitors, such as ceftazidime-avibactam, ceftolozane-tazobactam, ceftazidime-tazobactam, and meropenem-vaborbactam, has been suggested for the treatment of infections by extended-spectrum β-lactamases, carbapenemases, and AmpC producer bacteria. Nonetheless, they are not active against all carbapenemases, and there are reports of resistance to these combinations in clinical isolates.This review summarizes and discusses the in vitro and clinical evidence of the recently approved antibiotics, β-lactam inhibitors, and those in advanced phases of development for treating MDR infections caused by Gram-negative multi-drug resistant (MDR) bacterial species.

Phenotypic Detection of ESBL, AmpC, MBL, and Their Co-occurrence among MDR Enterobacteriaceae Isolates.

Background Emergence of extended-spectrum beta-lactamases (ESBLs), AmpC β-lactamases, and metallo-β lactamases (MBL), and their co-existence among members of Enterobacteriaceae pose newer diagnostic and therapeutic challenges. The present study examines the ESBL, AmpC, and MBL production by various phenotypic methods and their co-occurrence among the multidrug-resistant (MDR) Enterobacteriaceae clinical isolates. Materials and Methods Four hundred non-repetitive Enterobacteriaceae clinical isolates were collected from the Central Referral Hospital, Sikkim. The isolates were used for identification and their antibiotic susceptibility tests were performed according to the Clinical and Laboratory Standard Institute (CLSI) guidelines. ESBL was detected by double-disc synergy test (DDST) and phenotypic confirmatory disc-diffusion test (PCDDT), AmpC detection by AmpC E-test, and boronic acid disc diffusion (BD) test. MBL was detected using the imipenem–imipenem/EDTA disc and carba-NP tests. Results Around 76% were considered MDR. ESBL was seen in 58% and 50.4% based on DDST and phenotypic confirmation disc-diffusion test (PCDDT), respectively. AmpC was detected in 11.8% and 13.1% using a commercial E-test and boronic acid test, respectively. MBL were identified in 12.8% and 14.8% based on MBL imipenem-EDTA and carba-NP tests, respectively. Co-occurrence of ESBL and AmpC, ESBL and MBL, AmpC and MBL was seen in 5.2%, 11.5%, 1.3%, respectively, whereas a combination of these three β-lactamases was observed in only 0.3% of 304 MDR isolates. Conclusion The findings highlight a high prevalence of β-lactamases and their co-production among the Enterobacteriaceae , mainly in Klebsiella pneumoniae and Escherichia coli isolates. The study further highlights the necessity to identify the MDR β-lactamases stains for effective therapy in severe as well as mild bacterial infections, thereby enabling to reduce the risk of MDR in hospital and community settings.

Biofilm Production and its Association with Multi Drug Resistance in Pseudomonas aeruginosa among ICU Patients with Special Reference to ESBL, AmpC and MBL production

Multidrug resistant Pseudomonas aeruginosa is an alarming and emerging public health problem globally across the developing countries. Pseudomonas aeruginosa is still a major cause for nosocomial infection and approx 10-20% of these patients are admitted to the ICU’s. Bacterial isolates those are biofilm producers are more drug resistant than biofilm Non-producers. The aim of the present study was to evaluate the production of biofilm and β-lactamases (ESBL, MBL, AmpC) in multi drug resistant Pseudomonas aeruginosa isolated from ICU patients. The present cross-sectional prospective study was carried out in the Department of Microbiology, Santosh Medical College & Hospital, Ghaziabad, Uttar-Pradesh, India. A total of 115 isolates of P. aeruginosa were isolated from 502 clinical samples. After confirmation of MDR status of P. aeruginosa further processing for biofilm and beta lactamases was performed accordingly. Biofilm production was done by test tube method and tissue culture plate method along with phenotypic profiling of ESBL, MBL and AmpC was performed by disc potentiation test; IMP-EDTA combined disc test and Cefoxitin Cloxacillin Double Disc synergy test (CC-DDST) respectively. Out of 502 total human clinical samples 115 isolates were Pseudomonas aeruginosa giving the prevalence rate of 23%. Among 115 isolates of P. aeruginosa 60 (52%) were MDR phenotypes, Out of 60 MDR isolates 23 (38.3%) were ESBL producers, 22 (36.6%) were MBL producers, and 3(5%) were AmpC producers. Out of total 115 isolates 68(59%) isolates were biofilm producers and 47 (40.8%) were biofilm non-producers. Strict antibiotic policies with early detection of beta lactamases and detection of biofilm production should be performed regularly for all clinical isolates of Pseudomonas aeruginosa so as to guide antibiotic selection along with better management of severe infection in ICU patients.

Phenotypic characterization and antibiogram of extended spectrum ß-lactamase (ESBL)/AmpC-producing Escherichia coli isolated from sheep

This study aimed to isolate and characterize extended-spectrum ß-lactamases (ESBLs) and AmpC producing E. coli in sheep in Mosul city. A total of 260 milk and fecal samples were collected aseptically from healthy ewes (n=60), their respective lambs (n=60), and ewes with clinical mastitis (n=40). Standard bacterial isolation and identification on special culture media were performed to isolate ESBL/AmpC producing E. coli. While special antibiotic discs D68C MASTDISCS® Combi AmpC and ESBL ID set were used to characterize positive ESBL/AmpC E. coli. The results showed that 99/260 (38.1%) of tested samples were ESBL-E. coli positive and distributed as follows, 7/60 (11.7%) and 39/60 (65%) from milk and feces of clinically healthy ewes, respectively, and 37/60 (61.7%) from feces of clinically healthy lambs, while 4/40 (10%) and 12/40 (30%) from the milk and feces of ewes with clinical mastitis, respectively. However, we could not obtain any AmpC positive isolate from all tested samples. The high recovery percentages of ESBL from feces or milk of sheep reflect the arbitrary use of the antibiotic in sheep farming. This could significantly increase the resistance of the bacterial population that might represent a potential source for transmission of antibiotic resistance to humans.

Rapid identification of carbapenemases by CarbAcineto NP test and the rate of beta-lactamases among Acinetobacter baumannii from a teaching hospital.

Background and Objectives:Acinetobacter baumannii has emerged as a major organism accounting for hospital acquired infections particularly in intensive care units. Due to production of different kinds of beta lactamases these bacteria have developed drug resistance rendering the treatment of such infections very difficult and expensive. Rapid identification of A. baumannii producing such beta-lactamases is the need of the hour in reducing morbidity and mortality associated with A. baumannii infections.Materials and Methods:A. baumannii was isolated from clinical samples like endotracheal aspirates, sputum, urine, exudates using standard culture techniques. Identification and drug sensitivity was done using Vitek 2 system. All the isolates were subjected to detection of ESBLs using phenotypic confirmatory test, plasmid mediated AmpC beta-lactamase by AmpC disc test, Carbapenemase production by CarbAcineto NP Test and Modified hodge method.Results:149 A. baumannii isolates were analysed for antimicrobial susceptibility and various beta-lactamase production. Results were evaluated for statistical significance using Chi-Square and P value. 81.8% of isolates were from male patients with majority of them above 50 years of age. 88.5% of samples were from ventilator associated pneumonia patients. 83.8% of isolates were sensitive to tigecycline. Only 10% to 12% of isolates were sensitive to carbapenems. 23.4% of isolates were ESBL producers and 46.9% of them were AmpC producers. Modified Hodge test method identified 63.7% of A. baumannii as carbapenemase producers where as CarbAcineto NP test identified 63% and exibiting 94.74% sensitivity, 93.22% specificity when compared to Modified Hodge test.Conclusion:Multidrug resistant Acinetobacter spp. is on the rise. Present study showed that high percentage of drug resistance in A. baumannii could be due to production of ESBLs, AmpC and carbapenemases. Among all beta lactamases carbapenemase producers are more and quickly raising in A. baumannii. Rapid, cost effective assay which can be adopted in all clinical laboratories is critical to prevent their further transmission particularly in hospital environment.

Isolation of AmpC- and extended spectrum β-lactamase-producing Enterobacterales from fresh vegetables in the United States.

Vegetables may serve as a reservoir for antibiotic resistant bacteria and resistance genes. AmpC β-lactamases and extended spectrum beta-lactamases (ESBL) inactivate commonly used β-lactam antibiotics, including penicillins and cephalosporins. In this study, we determined the prevalence of AmpC and ESBL-producing Enterobacterales in retail vegetables in the United States. A total of 88 vegetable samples were collected for the screening of AmpC and ESBL-producing Enterobacterales using CHROMagar ESBL agar. These vegetables included washed ready-to-eat salad (23), microgreens/sprouts (13), lettuce (11), herbs (11), spinach (5), mushrooms (5), brussels sprouts (4), kale (3), and other vegetable samples (13). AmpC and ESBL activity in these isolates were determined using double disk combination tests. Two vegetable samples (2.27%), organic basil and brussels sprouts, were positive for AmpC-producing Enterobacterales and eight samples (9.09%), including bean sprouts, organic parsley, organic baby spinach, and several mixed salads, were positive for ESBL-producing Enterobacterales. Whole genome sequencing was used to identify the bacterial species and resistance genes in these isolates. Genes encoding AmpC β-lactamases were found in Enterobacter hormaechei strains S43-1 and 74-2, which were consistent with AmpC production phenotypes. Multidrug-resistant E. hormaechei strains S11-1, S17-1, and S45-4 possess an ESBL gene, blaSHV66 , whereas five Serratia fonticola isolates contain genes encoding a minor ESBL, FONA-5. In addition, we used shotgun metagenomic sequencing approach to examine the microbiome and resistome profiles of three spinach samples. We found that Pseudomonas was the most prevalent bacteria genus in the spinach samples. Within the Enterobacteriaceae family, Enterobacter was the most abundant genus in the spinach samples. Moreover, antibiotic resistance genes encoding 12 major classes of antibiotics, including β-lactam antibiotics, aminoglycoside, macrolide, fluoroquinolone, and others, were found in these spinach samples. Therefore, vegetables can serve as an important vehicle for transmitting antibiotic resistance. The study highlights the need for antibiotic resistance surveillance in vegetable products.

Molecular Epidemiology of Extended-Spectrum Beta-Lactamase and AmpC Producing Enterobacteriaceae among Sepsis Patients in Ethiopia: A Prospective Multicenter Study.

Extended-spectrum beta-lactamases (ESBLs) and AmpC producing Enterobacteriaceae are public health threats. This study aims to characterize ESBL and AmpC producing Enterobacteriaceae isolated from sepsis patients. A multicenter study was conducted at four hospitals located in central (Tikur Anbessa and Yekatit 12), southern (Hawassa) and northern (Dessie) parts of Ethiopia. Blood culture was performed among 1416 sepsis patients. Enterobacteriaceae (n = 301) were confirmed using MALDI-TOF and subjected for whole genome sequencing using the Illumina (HiSeq 2500) system. The overall genotypic frequencies of ESBL and AmpC producing Enterobacteriaceae were 75.5% and 14%, respectively. The detection of ESBL producing Enterobacteriaceae at Hawassa, Yekatit 12, Tikur Anbessa and Dessie was 95%, 90%, 82% and 55.8%, respectively. The detection frequency of blaCTX-M, blaTEM and blaSHV genes was 73%, 63% and 33%, respectively. The most frequently detected ESBL gene was blaCTX-M-15 (70.4%). The common AmpC genes were blaACT (n = 22) and blaCMY (n = 13). Of Enterobacteriaceae that harbored AmpC (n = 42), 71% were ESBL co-producers. Both blaTEM-1B (61.5%) and blaSHV-187 (27.6%) were the most frequently detected variants of blaTEM and blaSHV, respectively. The molecular epidemiology of ESBL producing Enterobacteriaceae showed high frequencies and several variants of ESBL and AmpC genes. Good antimicrobial stewardship and standard bacteriological laboratory services are necessary for the effective treatment of ESBL producing Enterobacteriaceae.

AmpC hyperproduction in a Cedecea davisae implant-associated bone infection during treatment: a case report and therapeutic implications

BackgroundData on antimicrobial resistance mechanisms are scanty for Cedecea spp., with very variable antibiotic resistance patterns documented. Here we report the first in vivo resistance evolution of a C. davisae clinical isolate in a patient with a complex hand trauma and provide insight in the resistance mechanism, leading to therapeutic implications for this pathogen.Case presentationCedecea davisae was isolated from a patient with hand trauma during a first surgical debridement. Six days after primary surgical treatment and under antimicrobial treatment with amoxicillin-clavulanic acid and later cefepime, follow up cultures yielded C. davisae which demonstrated a resistance development. The susceptible parental isolate and its resistant derivative were characterized by whole genome sequencing, ampC, ompC and ompF by RT- PCR. The resistant derivative demonstrated an A224G SNP in ampD, the transcriptional regulator of ampC, leading to a His75Arg change in the corresponding AmpD protein. AmpC transcription of the resistant derivative was 362-times higher than the susceptible isolate. Transcription levels of ompF and ompC were 8.5-fold and 1.3-fold lower, respectively, in the resistant derivative. Downregulation of OmpF putatively resulted from a mutation in the presumed promoter region upstream of the dusB-Fis operon, a proposed regulator for ompF.ConclusionsThis case demonstrates the in vivo resistance development of C. davisae within 7 days similar to that of the members of the Enterobacter cloacae complex. Our findings add valuable information for future therapeutic management of these opportunistic pathogens as they warrant the same empirical treatment as AmpC producers.

Trends of antimicrobial resistance in patients with complicated urinary tract infection: Suggested empirical therapy and lessons learned from a retrospective observational study in Oman.

Complicated urinary tract infection (cUTI) is defined as an infection associated with structural, functional, or metabolic abnormalities of the genitourinary tract. These infections are caused frequently by multidrug-resistant Gram-negative bacilli. The rapid emergence of extended-spectrum beta-lactamase (ESBL), AmpC, and carbapenemase (CR) producers has made the treatment of such infections increasingly more challenging. The aims of the present study were threefold: to assess the clinical profile, trends in etiology, and antimicrobial susceptibility profile in cUTI over the past 10 years at a tertiary care center in Oman as an interrupted time series on the one hand and to develop guidelines for empirical management of such cases on the other. We conducted a retrospective analysis of cUTI in patients presenting at Sultan Qaboos University Hospital over 3 years (2008, 2013, and 2018) covering a span of 10 years. Data were obtained from the patient's electronic records in the hospital information system. Analysis was done using the Statistical Package for Social Sciences program (SPSS), version 23. Among the 650 cases of cUTI, 284 (44%) were males and 366 (56%) were females, with dysuria being the most common symptom (34%). The biggest risk factor for developing cUTI was diabetes (35%). The predominant pathogen was Escherichia coli (53%), followed by Klebsiella spp. (16%), Enterococcus faecalis (7%), Pseudomonas aeruginosa (7%), Candida spp. (2%), and Enterobacter cloacae (2%). Over the years, E. coli emerged as the predominant ESBL and AmpC producer, Acinetobacter baumannii as the multidrug-resistant bug, and Klebsiella pneumoniae as the major carbapenem-resistant Enterobacterales (CRE) producer. Nitrofurantoin emerged as the most effective drug for cystitis. Aminoglycosides, piperacillin-tazobactam, and carbapenems demonstrated the highest activity with an overall resistance of less than 10%. Higher resistance (30%) was observed against cephalosporins, fluoroquinolones, and trimethoprim/sulfamethoxazole. Analysis of the 10-year trend threw up some unexpected results. As expected, resistance increased from 2008 to 2013. Surprisingly, however, antimicrobial resistance in 2018 was lower against majority of the antimicrobials compared to 2013. There is a paucity of data for developing evidence-based guidelines management of cUTI. Targeted antibiograms and not cumulative antibiograms are essential for promoting appropriate prescribing and optimizing patient care. The welcome decline in resistance may be attributed cascade reporting, introduction of more ID physicians. Another possibility is increased utilization of fluoroquinolones which spared the other groups of antimicrobials. Judicious heterogeneous mixing of antimicrobials should be spearheaded in both cystitis and pyelonephritis so that there is no undue pressure on one drug. We strongly recommend carbapenem-sparing protocols in treatment of cUTI when anticipating augmented resistance due to AmpC production. Synergistic combinations such as piperacillin-tazobactam plus aminoglycosides/fluoroquinolones may be prescribed. In sepsis, however, carbapenems are the drugs of choice.

Livestock and Poultry Milieus as Non-Hospital Sources of AmpC and ESBL Producers in Southeast Nigeria

Antimicrobial resistance (AMR) occurs when microorganisms fail to respond to the therapeutic onslaught of antibiotics. Extended-spectrum beta-lactamase (ESBL) and AmpC enzymes are important AMR mechanisms that erode the efficacy of important antibiotics. Here, we report on the detection and susceptibility of ESBL- and AmpC-producing bacteria from livestock and poultry environments. Bacteriological and molecular biology tools were used for the isolation and characterization of bacteria. Combined

Livestock and Poultry Milieus as Non-Hospital Sources of AmpC and Extended-Spectrum Beta-Lactamases Producers in Southeast Nigeria

Antimicrobial resistance (AMR) occurs when microorganisms fail to respond to the therapeutic onslaught of antibiotics. Extended-spectrum beta-lactamase (ESBL) and AmpC enzymes are important AMR mechanisms that erode the efficacy of important antibiotics. Here, we report on the detection and susceptibility of ESBL- and AmpC-producing bacteria from livestock and poultry environments. Bacteriological and molecular biology tools were used for the isolation and characterization of bacteria. Combined

Effect of the Different Plasmid-Mediated AmpC Beta-Lactamase Genotypes on the Phenotypic Detection of ESBL in Enterobacteriaceae Isolates.

Increasingly, Enterobacteriaceae isolates that are positive for the extended-spectrum-beta-lactamase (ESBL) by phenotypic screening tests yield a negative result when tested with the reference Clinical and Laboratory Standards Institute (CLSI) ESBL confirmatory test. The aim is to determine to what extent the different plasmid AmpC (pAmpC) genotypes could affect the CLSI ESBL confirmatory test for detection of the ESBL phenotype in ESBL/pAmpC co-producers. A total of 253 Enterobacteriaceae isolates were screened for ESBL and AmpC production according to CLSI guidelines. Out of 186 ESBL and AmpC-screen-positive isolates, 96 isolates were selected for ESBL confirmation by the combined disc diffusion test (CDDT) as well as for detection of the most common ESBL and pAmpC encoding-genes by multiplex PCR. Out of the 96 ESBL/AmpC-screen-positive isolates, all (100%) were positive for at least one of the investigated ESBL genes, and 88 (91.7%) were positive for any of the investigated pAmpC genes. CDDT correctly identified ESBL phenotype more frequently in non-pAmpC carriers than pAmpC carriers (75% vs. 52.3%). CIT alone-containing isolates were associated more with non-confirmed ESBL phenotype rather than confirmed ESBL phenotype (76.2% vs. 30.4%, p < 0.001), especially when co-harbored blaCTXM alone (76.9% vs. 33.3%, p < 0.001) or both blaCTXM/blaSHV genes (100% vs. 0%). On the other hand, DHA-carrying isolates were more associated with confirmed ESBL phenotype than with non-confirmed ESBL phenotype when co-harboring either blaCTXM alone (47.6% vs. 0%, p < 0.001) or blaCTXM/blaSHV genes (100% vs. 0%, p = 0.022) or blaCTX-M/blaTEM genes (100% vs. 0%, p = 0.03). For ESBL/pAmpC co-producers of Enterobacteriaceae, CDDT results vary with the type of pAmpC genes and with different ESBL/pAmpC genotype combinations. Therefore, the ESBL-screening test is more sensitive than the CDDT in detecting ESBL phenotype among ESBL/pAmpC coproducers of Enterobacteriaceae.

Prevalence and molecular characterization of extended-spectrum β-lactamase (ESBL) producing Escherichia coli isolated from dogs suffering from diarrhea in and around Kolkata.

Dogs are the favorite companion animals among humans. The close interaction between dogs and people increases the risk of antibiotic resistance spreading. Surveillance for antimicrobial resistance and the identification of ESBL-producing Escherichia coli as an indicator bacterium is an important tool for managing antimicrobial drug therapy. The present study targeted to identify and characterize ESBL-producing E. coli among dogs suffering from diarrhea in and around Kolkata. Isolation and identification of E. coli from dogs suffering from diarrhea (n=70) along with screening for the production of both ESBL and AmpC. The isolates were further characterized through antimicrobial resistance profiling, resistance genes (bla CTX-M, bla TEM, and bla SHV) screening, and phylogenetic group study. Among the 70 isolates, 21 (30%) were confirmed ESBL producers. An antibiogram typing of ESBL-producing E. coli revealed that the majority of them were resistant to norfloxacin (85.7%) followed by tetracycline (61.90%), doxycycline (57.14%), piperacillin/tazobactam (52.38%), cotrimoxazole (47.62%), gentamicin (42.62%), amikacin (23.81%), and chloramphenicol (19.05%). Major resistance genes included bla CTX-M (100%), bla TEM (28.57%), and bla SHV (9.50%). The predominant phylogenetic groups were phylogroup A (76%) followed by phylogroup D (24%). The current investigation reported a high prevalence of both ESBL and AmpC β-lactamase (AmpC) producing E. coli, co-resistance to a distinct group of antibiotics, and co-existence of different ESBL genes in dogs. Our findings highlight the importance of diagnostic antimicrobial susceptibility testing for proper antimicrobial therapy and to prevent antimicrobial resistance from spreading to humans from dogs in Kolkata and the surrounding area.